/Engine/Source/Runtime/MovieScene/Public/EntitySystem/MovieScenePropertyRegistry.h
Type aliases for a property that resolved to either a fast pointer offset (type index 0), or a custom property index (specific to the path of the property - type index 1)
typedef [TVariant](API\Runtime\Core\Misc\TVariant)< uint16, [UE::MovieScene::FCustomPropertyIndex](API\Runtime\MovieScene\EntitySystem\FCustomPropertyIndex) > FResolvedFastProperty